“The cement boat”
SS Palo Alto was a concrete ship built as a tanker at the end of World War I. Completed too late to see war service, she was mothballed until 1929, when she was intentionally grounded off a Northern California beach, becoming part of a pleasure pier entertainment complex. Wikipedia
Launched: May 29, 1919 Length: 420′
Fate: Grounded as a fishing pier at Seacliff Beach in Aptos, California
Depth: 35 ft (11 m)